Melania Trump has accused the US president's first wife Ivana of "attention seeking and self-serving noise" after the first Mrs Trump called herself the "first lady".
In an interview ahead of the release of her memoir Raising Trump, the president's ex-wife boasted of having a "direct number" to Donald Trump at the White House and of speaking to him once a fortnight.
She told ABC's Good Morning America: "I have the direct number to White House but I don't really want to call him there because Melania is there and I don't really want to cause any kind of jealousy or something like that because I'm basically first Trump wife, OK? I'm first lady, OK?"
The president's current wife Melania rebuked his ex-wife, married to Mr Trump from 1977 to 1992, in a scathing statement given to CNN by her communications director Stephanie Grisham.
She mentioned the first lady's son with Mr Trump, 11-year-old Barron, saying: "Mrs Trump has made the White House a home for Barron and the President. She loves living in Washington, DC, and is honoured by her role as first lady of the United States. She plans to use her title and role to help children, not sell books."
She added: "There is clearly no substance to this statement from an ex, this is unfortunately only attention-seeking and self-serving noise."
Ivana Trump has three sons with the US president - Donald Jr, Ivanka and Eric - but the couple split in the early 1990s after Mr Trump's highly publicised affair with Marla Maples.
Attention fell on the split during the 2016 election, when it was claimed Ivana Trump signed a deposition during divorce proceedings saying Mr Trump raped her.
She later said she did not mean rape in the "literal or criminal" sense, and the US president has repeatedly denied the allegation.
